Core for pliable strip material



Aprrfifl M, 1967 R. L. KEECH 7 3,313,497

CORE FOR PLIABLE STRIP MATERIAL Filed June 1, 1965 I N VE N TOR 905527 A .KEECH Y United States Patent Ofi" 3,313,497 Patented Apr. 11, 1967 3,313,497 CORE FOR PLIABLE STRIP MATERIAL Robert L. Keech, White Bear Lake, Minn., assignor to Minnesota Mining and Manufacturing Company, St. Paul, Mum, a corporation of Delaware Filed June 1, 1965, Ser. No. 460,442 5 Claims. (Cl. 242-685) This invention relates to cores on which pliable strip material is wound in roll form and more particularly relates to cores which prevent the harmful distortion of such strip materials wound thereon.

Soft, pliable adhesive stripping is commonly used for such applications as caulking, weather stripping, or as sealants for automobile Windshields, etc. Such strip materials are generally wound in roll form in order that they conveniently may be shipped and dispensed. It has been found that when such strip materials are wound around a cylindrical core, the innermost wrap of the material becomes distorted at the point where the strip must bridge the step from the core to the top of the innermost wrap to begin the second wrap of strip material around the core. At this point an approximately triangular space is left beneath this bridge between the core and the inner end of the sealant. As pressure is applied during the course of winding successive wraps of material on the core, the innermost end and the first wrap which laps the innermost end tend to become distorted. As a result, the material when unwound from the core is not uniform, and the distorted portion is not usable in many applications where uniformity is required, as in the sealing of automobile Windshields.

The present invention provides a core around which tacky, pliable adhesive mate-rials can be wound with a minimum of distortion so that the entire length thereof can be used after unwinding from the core, thus eliminating the waste caused by conventional cores. The cores of the present invention can be manufactured from economical materials such as molded plastic or fiberboard. The shape of the cores makes them readily adaptable for use with conventional dispensers.

The invention will be further described in conjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view of a core formed in accordance with one embodiment of the present invention;

FIGURE 2 is an end view of a core of the invention with adhesive strip material wound thereon.

Referring now to the drawings in detail, a core of the present invention is designated by numeral 10. In its preferred form, core is in the shape of a hollow cylinder. A radially depressed portion 11 is formed at one point in the circumference of the core. In the case of a plastic core 11 can conveniently be molded into the surface of the core, as shown in the embodiment of FIG- URE 2, while in the case of a fiberboard core the indentation can more easily be made by first forming the core in cylindrical form and then forming at one point in the circumference a depressable tab as shown in FIGURE 1. The tab is formed by cutting a rectangular area along three sides. As seen from the drawing the indentation is elongated in a direction circumferential to the core. The free end of the tab forms a deep end 12 of the indentation, which becomes progressively more shallow toward the opposite end 13. The shallow end 13 of the depression is an arcuate extension of the outer surface of the core while at the deep end 12 there is a step formed in the surface of the core.

The indentation may be either molded into the surface of the core which is preferably formed from an easily moldable composition such as a thermoplastic organic resin or formed by cutting through the core depending on the material from which the core is formed. In the event that the indentation is formed by molding or otherwise making the same a fixed part of the core, it is preferred to form the deep end 12 so that the depth thereof will be approximately equal to the thickness of the strip material which is to be wound on the core. It will be seen, however, that if the bottom of the indentation is formed by a tab defined by three cuts in the core material, the indentation will be self-adjusting as to the depth thereof at the deep end. The free end of the tab can easily be depressed a distance approximately equal to the thickness of the strip. Therefore, the core can be used in connection with strips of varying thickness.

The core could alternatively be formed from two concentric cores, the outermost of which is provided with a spirally shaped, stepped surface and the innermost of which is circular to facilitate rotation of the core about its central axis when mounted on a suitable shaft. These concentric cores would generally be held in position by flanges.

As seen in FIGURE 2 the innermost end 20 of adhesive strip 21 is positioned at the deep end of the indentation and the same is wrapped on the core in such fashion that the end of the strip will be cradled within the indentation. It is seen that as the first wrap of adhesive material is wound around the core it can pass smoothly from the core surface adjacent the deep end of the indentation to the upper surface of end 20 as the second wrap of the material is begun. In the case of tacky adhesive strip materials, it is generally necessary to position an interleaving sheet or liner 22 on the top of the adhesive strip in order to prevent the successive coils of strip material from adhering to each other. In the case of fiberboard cores it is usually necessary to coat the outer surface of the core with an agent that will prevent adhesion of the strip to the core. Such agents are well known to those skilled in the art.

It will be apparent to those skilled in the art that the present invention can be used in conjunction with cores having cross sections other than circular, for example, elliptical.

While various illustrative embodiments of the invention have been shown in the drawings and described in detail herein, the invention is susceptible of embodiment in different forms. It is to be understood that the present disclosure is an exemplification of the principles of the in vention and is not intended to limit the invention to the particular embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

What is claimed is:

1. A hollow cylindrical core for thick pliable adhesive strips having a radially depressible tab formed by cuts through the thickness thereof, two of said cuts being substantially parallel to the ends of said core, said two cuts being intreconnected by a third transverse cut, the tab within the area defined by said cuts being radially depressed to form an indentation adapted to receive the end of an adhesive strip wrapped around said core.

2. A core of claim 1 formed from fiberboard.

3. A roll of pliable adhesive strip material wound on a hollow cylindrical core, said core having a tab therein being formed by cuts through the thickness of said core, two of said cuts being parallel to said strip material, said parallel cuts being interconnected by a third transverse cut, the end of said tab opposite said third cut being an integral part of the surface of said core, the free end of said tab being flexed inwardly forming a depression in the surface of said core, the inner end of said adhesive strip material being positioned in said depression.

4. The roll of claim 3 wherein said free end of said tab is depressed a distance approximately equal to the thickness of said strip material.

9 4 a 5. A hollow annular core for soft pliable strip material, References Cite-:1 by the Examiner the outer surface of said core bein adapted to receive said strip material, said surface havirig a radially 'depress- UNITED STATES PATENTS ible portion in the circumference thereof defined by two 1,263,798 4/1918 Otto 242--86 X circumferentially extending cuts through said surface, said 5 2 139 547 2/1942 Fischer X two cuts being interconnected by a third transverse cut, u

the portion of the core Within the area defined by said 2501596 3/1950 Danny 242 77 cuts being radially depressible to form an indentation in 1 said surface adapted to receive the end of an adhesive STANLEY GILREATH Pnmam Examiner strip Wrapped around said core. 10 

1. A HOLLOW CYLINDRICAL CORE FOR THICK PLIABLE ADHESIVE STRIPS HAVING A RADIALLY DEPRESSIBLE TAB FORMED BY CUTS THROUGH THE THICKNESS THEREOF, TWO OF SAID CUTS BEING SUBSTANTIALLY PARALLEL TO THE ENDS OF SAID CORE, SAID TWO CUTS BEING INTERCONNECTED BY A THIRD TRANSVERSE CUT, THE TAB WITHIN THE AREA DEFINED BY SAID CUTS BEING RADIALLY DEPRESSED TO FORM AN INDENTATION ADAPTED TO RECEIVE THE END OF AN ADHESIVE STRIP WRAPPED AROUND SAID CORE. 